What is Caffeine?

Caffeine is a chemical found in coffee, tea, cola, guarana, mate, and other products.

Caffeine is most commonly used to improve mental alertness, but it has many other uses. Caffeine is used by mouth or rectally in combination with painkillers (such as aspirin and acetaminophen) and a chemical called ergotamine for treating migraine headaches. It is also used with painkillers for simple headaches and preventing and treating headaches after epidural anesthesia.

Some people use caffeine by mouth for asthma, gallbladder disease, attention deficit-hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), low oxygen levels in the blood due to exercise, Parkinson's disease, memory, cramping, liver cirrhosis, Hepatitis C, stroke, recovery after surgery, decreasing pain, muscle soreness from exercise, age-related mental impairment, shortness of breath in newborns, and low blood pressure. Caffeine is also used for weight loss and type 2 diabetes. Very high doses are used, often in combination with ephedrine, as an alternative to illegal stimulants.

Caffeine is one of the most commonly used stimulants among athletes. Taking caffeine, within limits, is allowed by the National Collegiate Athletic Association (NCAA). Urine concentrations over 15 mcg/mL are prohibited. It takes most people about 8 cups of coffee providing 100 mg/cup to reach this urine concentration.

Caffeine creams are applied to the skin to reduce redness and itching in dermatitis.

In foods, caffeine is used as an ingredient in soft drinks, energy drinks, and other beverages.

People with voice disorders, singers, and other voice professionals are often advised against using caffeine. However, until recently, this recommendation was based only on hearsay. Now developing research seems to indicate that caffeine may actually harm voice quality. But further study is necessary to confirm these early findings.

Effective for...

Migraine headache. Taking caffeine by mouth together with pain relievers such aspirin and acetaminophen is effective for treating migraines. Caffeine is an FDA-approved product for use with pain relievers for treating migraine headaches.

Headache following surgery. Using caffeine by mouth or intravenously is effective for preventing headaches following surgery. Caffeine is an FDA-approved product for this use in people who regularly consume products that contain caffeine.

Likely Effective for...

Mental alertness. Research suggests that drinking caffeinated beverages throughout the day keeps the mind alert. Combining caffeine with glucose as an "energy drink" seems to improve mental performance better than either caffeine or glucose alone.

Possibly Effective for...

Asthma. Caffeine appears to improve airway function for up to 4 hours in people with asthma.

Athletic performance. Taking caffeine seems to increase physical strength and endurance and might delay exhaustion. It might also reduce feelings of exertion and improve performance during activities such as cycling, running, playing soccer, and golfing. However, caffeine does not seem to improve performance during short-term, high-intensity exercise such as sprinting and lifting.

Diabetes. Drinking beverages that contain caffeine is linked with a lower risk of developing type 2 diabetes. It appears that the more caffeine that is consumed, the lower the risk. Although caffeine might help prevent type 2 diabetes, it might not be effective in treating type 2 diabetes. Research on the effects of caffeine in people with type 1 diabetes is inconsistent. Some research shows benefit, while other research does not.

Gallbladder disease. Drinking beverages that provide at least 400 mg of caffeine daily seems to reduce the risk of developing gallstone disease. The effect seems to be dose-dependent. Taking 800 mg of caffeine daily seems to work best.

Memory. Taking 200 mg of caffeine by mouth daily seems to improve memory in some people with outgoing personalities and college students.

Breathing problems in infants. Caffeine given by mouth or intravenously (by IV) appears to improve breathing in infants born too early. It seems to reduce the number of episodes of shortness of breath by at least 50% over 7-10 days of treatment. However, caffeine does not seem to reduce the risk of premature infants developing breathing problems.

Pain. Research suggests that taking caffeine together with painkillers can reduce pain.

Parkinson's disease. Some research suggests that people who drink caffeinated beverages have a decreased risk of Parkinson's disease. However, this reduced risk is not observed in people who smoke cigarettes.

Headache after epidural anesthesia. Taking caffeine by mouth or intravenously seems to help prevent headache after epidural anesthesia.

Weight loss. Taking caffeine in combination with ephedrine seems to help reduce weight, short-term. Taking 192 mg of caffeine in combination with 90 mg of ephedra daily for 6 months seems to cause a modest weight reduction (5.3 kg or 11.66 pounds) in overweight people. This combination, along with limiting fat intake to 30 percent of calories and moderate exercise, also seems to reduce body fat, decrease "bad" low-density lipoprotein (LDL) cholesterol, and increase "good" high-density lipoprotein (HDL) cholesterol. However, there can be unwanted side effects. Even in carefully screened and monitored otherwise healthy adults, caffeine/ephedra combinations can cause changes in blood pressure and heart rate.

Possibly Ineffective for...

Attention deficit-hyperactivity disorder (ADHD). Most research suggests that caffeine does not reduce ADHD symptoms in children. The use of caffeine in adolescents and adults with ADHD has not been studied.

Insufficient Evidence to Rate Effectiveness for...

Age-related mental problems. Early research suggests that consuming more than 371 mg of caffeine daily might help prevent mental decline in elderly women compared to those who consume less caffeine. Drinking caffeinated coffee is linked to slower mental decline, but not other caffeinated products such as tea.

Cancer pain. Early research shows that receiving 200 mg of caffeine intravenously once daily for 2 days might reduce pain in people with advanced cancer.

Depression. Some research suggests that caffeine intake is linked with an increased occurrence of depression symptoms in children. However, other research suggests that caffeinated coffee intake is linked to a decreased occurrence of depression in adults.

Low levels of oxygen in the blood caused by exercise. Early research shows that taking caffeine may improve breathing during exercise, but does not affect blood levels of oxygen in athletes with low blood oxygen levels during exercise

Muscle soreness during exercise. Some early research suggests that taking moderate doses of caffeine can reduce muscle pain during exercise, while lower doses may not help.

Hepatitis C. Research suggests that higher intake of caffeine from coffee is linked to reduced liver scarring in people with hepatitis C.

Headaches while sleeping. Some early evidence suggests that drinking a cup of coffee before bed or upon waking up might help alleviate pain associated with headaches that occur during sleep.

Cramping due to narrowed arteries (intermittent claudication). Taking a single 6 mg dose of caffeine by mouth seems to improve walking and muscle strength in people with aching and cramping due to narrowed or blocked arteries.

Liver cirrhosis. Research suggests that drinking coffee might reduce the risk for liver cirrhosis. However, it is unclear if this effect is due to caffeine or other components of coffee.

Obsessive-compulsive disorder (OCD). Early research shows that adding caffeine to conventional therapy seems to decrease the severity of OCD symptoms.

Stoke. Research shows that increased caffeinated or decaffeinated coffee intake is linked to a decreased risk of stroke in women. However, it is not clear if the effect is due to caffeine.

How does Caffeine work?

Caffeine works by stimulating the central nervous system (CNS), heart, muscles, and the centers that control blood pressure. Caffeine can raise blood pressure, but might not have this effect in people who use it all the time. Caffeine can also act like a "water pill" that increases urine flow. But again, it may not have this effect in people who use caffeine regularly. Also, drinking caffeine during moderate exercise is not likely to cause dehydration.

Are there safety concerns?

Caffeine is LIKELY SAFE for most adults when used appropriately.

Caffeine is POSSIBLY UNSAFE when taken by mouth for a long time or in fairly high doses. Caffeine can cause insomnia, nervousness and restlessness, stomach irritation, nausea and vomiting, increased heart rate and respiration, and other side effects. Caffeine can make sleep disorders in patients with acquired immunodeficiency syndrome (AIDS) worse. Larger doses might cause headache, anxiety, agitation, chest pain, and ringing in the ears.

Caffeine is LIKELY UNSAFE when taken by mouth in very high doses as it can cause irregular heartbeats and even death.

Special Precautions & Warnings:

Children: Caffeine is POSSIBLY SAFE when taken appropriately by mouth or intravenously (by IV), as well as when used in amounts commonly found in foods and beverages.

Pregnancy and breast-feeding: Caffeine is POSSIBLY SAFE in pregnant or breast-feeding women when used daily amounts of less than 200 mg. This is about the amount in 1-2 cups of coffee. Consuming larger amounts during pregnancy or when breast-feeding is POSSIBLY UNSAFE. When consumed in larger amounts during pregnancy, caffeine might increase the chance of miscarriage and other problems. Also, caffeine can pass into breast milk, so nursing mothers should closely monitor caffeine intake to make sure it is on the low side. High intake of caffeine by nursing mothers can cause sleep disturbances, irritability, and increased bowel activity in breast-fed infants.

Anxiety disorders: Caffeine might make these conditions worse. Use with care.

Bipolar disorder: Too much caffeine might make this condition worse. In one case, a 36-year-old man with controlled bipolar disorder was hospitalized with symptoms of mania after drinking several cans of an energy drink containing caffeine, taurine, inositol, and other ingredients (Red Bull Energy Drink) over a period of 4 days. Use caffeine with care and in low amounts if you have bipolar disorder.

Bleeding disorders: There is concern that caffeine might aggravate bleeding disorders. Use caffeine with care if you have a bleeding disorder.

Diabetes: Some research suggests that caffeine may affect the way the body uses sugar and might worsen diabetes. However, the effect of caffeinated beverages and supplements has not been studied. If you have diabetes, use caffeine with caution.

Diarrhea: Caffeine, especially when taken in large amounts, can worsen diarrhea.

Epilepsy: People with epilepsy should avoid using caffeine in high doses. Low doses of caffeine should be used cautiously.

Glaucoma: Caffeine increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes after drinking caffeinated beverages.

High blood pressure: Consuming caffeine might increase blood pressure in people with high blood pressure. However, this effect might be less in people who use caffeine regularly.

Loss of bladder control. Caffeine can make bladder control worse by increasing frequency of urination and the urge to urinate.

Irritable bowel syndrome (IBS): Caffeine, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.

Weak bones (osteoporosis): Caffeine can increase the amount of calcium that is flushed out in the urine. If you have osteoporosis or low bone density, caffeine should be limited to less than 300 mg per day (approximately 2-3 cups of coffee). It is also a good idea to get extra calcium to make up for the amount that may be lost in the urine. Older women with an inherited disorder that affects the way vitamin D is used should use caffeine with caution. Vitamin D works with calcium to build bones.

Are there any interactions with medications?

EphedrineInteraction Rating:
Major Do not take this combination.

Stimulant drugs speed up the nervous system. Caffeine and ephedrine are both stimulant drugs. Taking caffeine along with ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.

Adenosine (Adenocard)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine might block the effects of adenosine (Adenocard). Adenosine (Adenocard) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming caffeine-containing products at least 24 hours before a cardiac stress test.

The body breaks down caffeine to get rid of it. Some antibiotics might decrease how quickly the body breaks down caffeine. Taking these antibiotics along with caffeine can increase the risk of side effects including jitteriness, headache, increased heart rate, and other side effects.

Carbamazepine (Tegretol)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Carbamazepine is used to treat some seizures. Caffeine may lower the effects of carbamazepine or increase how susceptible a person is to seizures. In theory, taking caffeine with carbamazepine can reduce its effects and increase the risk of seizures in some people.

Cimetidine (Tagamet)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Cimetidine (Tagamet) can decrease how quickly your body breaks down caffeine. Taking cimetidine (Tagamet) along with caffeine might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

Clozapine (Clozaril)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down clozapine (Clozaril) to get rid of it. Caffeine seems to decrease how quickly the body breaks down clozapine (Clozaril). Taking caffeine along with clozapine (Clozaril) can increase the effects and side effects of clozapine (Clozaril).

Dipyridamole (Persantine)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine might block the affects of dipyridamole (Persantine). Dipyridamole (Persantine) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming caffeine-containing products at least 24 hours before a cardiac stress test.

Disulfiram (Antabuse)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Disulfiram (Antabuse) can decrease how quickly the body gets rid of caffeine. Taking caffeine along with disulfiram (Antabuse) might increase the effects and side effects of caffeine including jitteriness, hyperactivity, irritability, and others.

EstrogensInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Taking caffeine along with estrogens might cause jitteriness, headache, fast heartbeat, and other side effects. If you take estrogens limit your caffeine intake.

EthosuximideInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Ethnosuximide is used to control certain types of seizures. Caffeine might lower the effects of ethnosuximide or increase how susceptible a person is to seizures. In theory, taking caffeine with ethnosuximide might reduce its effects and increase the risk of seizures.

FelbamateInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Felbamate is used to control certain types of seizures. Caffeine might lower the effects of felbamate or increase how susceptible a person is to seizures. In theory, taking caffeine with felbamate might reduce its effects and increase the risk of seizures.

Flutamide (Eulexin)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down flutamide (Eulexin) to get rid of it. Caffeine might decrease how quickly the body breaks down flutamide (Eulexin). Taking caffeine along with flutamide (Eulexin) might cause too much flutamide (Eulexin) in the body, and increase the risk of side effects of flutamide (Eulexin).

Fluvoxamine (Luvox)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Fluvoxamine (Luvox) can decrease how quickly the body breaks down caffeine. Taking caffeine along with fluvoxamine (Luvox) might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

LithiumInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

You body naturally gets rid of lithium. Caffeine can increase how quickly your body gets rid of lithium. If you take products that contain caffeine and you take lithium, stop taking caffeine products slowly. Stopping caffeine too quickly can increase the side effects of lithium.

Medications for asthma (Beta-adrenergic agonists)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine can stimulate the heart. Some medications for asthma can also stimulate the heart. Taking caffeine with some medications for asthma might cause too much stimulation and cause heart problems.

Medications for depression (MAOIs)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine can stimulate the body. Some medications used for depression can also stimulate the body. Taking caffeine along with some medications for depression might cause serious side effects including fast heartbeat, high blood pressure, nervousness, and others.

Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.

Pentobarbital (Nembutal)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The stimulant effects of caffeine can block the sleep-producing effects of pentobarbital.

PhenobarbitalInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Phenobarbital is used to control some types of seizures. Caffeine might lower the effects of phenobarbital or increase how susceptible a person is to seizures. In theory, taking caffeine with phenobarbital might reduce its effects and increase the risk of seizures.

PhenylpropanolamineInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking caffeine along with phenylpropanolamine might cause too much stimulation and increase heartbeat, blood pressure, and cause nervousness.

PhenytoinInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Phenytoin is used to control some types of seizures. Caffeine might lower the effects of phenytoin or increase how susceptible a person is to seizures. In theory, taking caffeine with phenytoin might reduce its effects and increase the risk of seizures.

Riluzole (Rilutek)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down riluzole (Rilutek) to get rid of it. Taking caffeine along with riluzole (Rilutek) might decrease how fast the body breaks down riluzole (Rilutek) and increase the effects and side effects of riluzole (Rilutek).

Stimulant drugsInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Stimulant drugs speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and speed up your heart rate. Caffeine might also speed up the nervous system. Taking caffeine along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with caffeine.

TheophyllineInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Caffeine works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. Taking theophylline along with caffeine might increase the effects and side effects of theophylline.

Ticlopidine (Ticlid)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Ticlopidine (Ticlid) can decrease how fast the body gets rid of caffeine. Taking caffeine along with ticlopidine (Ticlid) can increase the risk of caffeine side effects.

ValproateInteraction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

Valproate is used to control some types of seizures. Caffeine can lower the effects of valproate or increase how susceptible a person is to seizures. In theory, taking caffeine with valproate might reduce its effects and increase the risk of seizures.

The body breaks down caffeine to get rid of it. Verapamil (Calan, Covera, Isoptin, Verelan) can decrease how quickly the body gets rid of caffeine. Taking caffeine along with verapamil (Calan, Covera, Isoptin, Verelan) can increase the risk of side effects for caffeine including jitteriness, headache, and an increased heartbeat.

Water pills (Diuretic drugs)Interaction Rating:
Moderate Be cautious with this combination.Talk with your health provider.

AlcoholInteraction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking caffeine along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.

Birth control pills (Contraceptive drugs)Interaction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. Taking caffeine along with birth control pills can cause jitteriness, headache, fast heartbeat, and other side effects.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.

Fluconazole (Diflucan)Interaction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Fluconazole (Diflucan) might decrease how quickly the body gets rid of caffeine. Taking caffeine along with fluconazole (Diflucan) might cause caffeine to stay in to body too long and increase the risk of side effects such as nervousness, anxiety, and insomnia.

Caffeine is changed and broken down by the liver. Some drugs decrease how quickly the liver changes and breaks down certain medications and supplements. Taking caffeine along with these drugs might slow the processing of caffeine and increase caffeine levels.

Some of these medications that affect the liver include fluvoxamine, mexiletine, clozapine, psoralens, furafylline, theophylline, idrocilamide, and others.

Medications for diabetes (Antidiabetes drugs)Interaction Rating:
Minor Be cautious with this combination.Talk with your health provider.

Caffeine might increase or decrease blood sugar. Diabetes medications are used to lower blood sugar. Taking caffeine with some medications for diabetes might increase or decrease the effectiveness of the diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

MetforminInteraction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Metformin can decrease how quickly the body breaks down caffeine. Taking metformin along with caffeine might increase the effects and side effects of caffeine.

MethoxsalenInteraction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Methoxsalen can decrease how quickly the body breaks down caffeine. Taking methoxsalen along with caffeine might increase the effects and side effects of caffeine.

Mexiletine (Mexitil)Interaction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Mexiletine (Mexitil) can decrease how quickly the body breaks down caffeine. Taking Mexiletine (Mexitil) along with caffeine might increase the effects and side effects of caffeine.

PhenothiazinesInteraction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Phenothiazines can decrease how quickly the body breaks down caffeine. Taking phenothiazines along with caffeine might increase the effects and side effects of caffeine.

Terbinafine (Lamisil)Interaction Rating:
Minor Be cautious with this combination.Talk with your health provider.

The body breaks down caffeine to get rid of it. Terbinafine (Lamisil) can decrease how fast the body gets rid of caffeine. Taking caffeine along with terbinafine (Lamisil) can increase the risk of caffeine side effects including jitteriness, headache, increased heartbeat, and other effects.

TiagbineInteraction Rating:
Minor Be cautious with this combination.Talk with your health provider.

Tiagabine is used to control some types of seizures. Caffeine does not seem to influence the effects of tiagabine. However, long-term caffeine use might increase blood levels of tiagbine.

Dosing considerations for Caffeine.

The following doses have been studied in scientific research:

ADULTS

BY MOUTH:

General: One cup of brewed coffee provides from 95-200 mg of caffeine. An 8-ounce serving of black tea provides from 40-120 mg of caffeine. An 8-ounce serving of green tea provides 15-60 mg of caffeine. Soft drinks such as cola provide from 20-80 mg of caffeine per 12 ounce serving. Sports or energy drinks typically provide from 48-300 mg of caffeine per serving.

For headache: Does of 100-250 mg caffeine daily have been used. Caffeine has also been used together with acetaminophen, aspirin, ergotamine, and sumatriptan.

For headache after epidural anesthesia: Caffeine 300 mg has been used.

For mental alertness: Doses of 100-250 mg caffeine daily have been used. Caffeine has also been taken together with taurine, glucose and L-theanine.

For asthma: Caffeine has been taken in doses of 9 mg/kg.

For improving athletic performance: 1.6-10 mg/kg or more has been used. However, doses in excess of 800 mg per day can result in urine levels greater than the 15 mcg/mL allowed by the National Collegiate Athletic Association.

For preventing gallstone disease: Consumption of 400 mg or more of caffeine daily has been used.

For memory: 65-200 mg of caffeine has been used.

For pain: Doses of 50-130 mg caffeine have been used with pain relievers including acetaminophen, propyphenazone, and ibuprofen.

For preventing Parkinson's disease: Men drinking 421-2716 mg of total caffeine daily have the lowest risk of developing Parkinson's disease, when compared to other men. However, men who drink as little as 124-208 mg of caffeine daily also have a significantly lower chance of developing Parkinson's disease. In women, moderate caffeine intake per day (1-3 cups of coffee per day) seems to be best.

Headache after surgery: 200 mg of caffeine has been given intravenously to prevent headache after surgery.

CHILDREN

BY IV:

For breathing problems in infants: Caffeine is given intravenously (by IV) by healthcare providers for breathing problems in infants and for headache after epidural anesthesia.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.